As is known, compensation components are high-voltage components with a dielectric strength of more than 300 V which are distinguished by an on resistance reduced by approximately one order of magnitude compared with conventional high-voltage components and are therefore extremely advantageous. In such compensation components, charge compensation is provided to the greatest possible extent in the drift zone thereof, so that, by way of example, p-conducting compensation regions are incorporated into the n-conducting drift zone of an n-channel transistor; the dopant quantities in said p-conducting compensation regions are set in such a way that there is charge compensation with the n-conducting surroundings of the drift zone.
In a vertical component, the compensation regions preferably comprise pillar-type zones located in the drift path in the region between the body zone and the drain zone.
In order to fabricate such a compensation component, at the present time use is preferably made of the so-called construction technique, which comprises a repeated succession of a process sequence with a masked low-energy implantation and the deposition of an epitaxial layer. The construction technique is complicated, this being attributable to said multiple succession of the process sequence.
In the case of the construction technique, by way of example, n-conducting epitaxial layers are deposited in order to fabricate an n-channel transistor, into which epitaxial layers, in each case after the deposition thereof, p-conducting compensation regions are introduced by ion implantation in such a way that they assume a pillar-type structure. Of course, it is also possible, however, to deposit a p-conducting epitaxial layer and to incorporate n-conducting compensation regions therein by means of implantation.
As is known, there are even further doping methods besides doping with the aid of epitaxy and ion implantation. One of these doping methods provides, in order to fabricate an n-type doping, a high-energy proton irradiation in silicon as semiconductor body. This is because during such a proton irradiation, intrinsic defect complexes which act as n-type dopants are produced in silicon. In this case, the proton irradiation has the advantage that the protons that are radiated in penetrate deeply into the silicon body even at relatively low energies. Thus, it shall be specified as an example that an implantation energy of 1.7 MeV leads to a penetration depth in silicon of about 36 μm.
Specifically, DE 100 25 567 A1 discloses a method for fabricating deeply doped n-conducting regions into a p-conducting semiconductor body, in which said n-conducting regions are produced by means of a masked implantation of protons and a subsequent heat treatment at temperatures of between 200 and 380° C. An indiffusion of hydrogen is performed at temperatures of between 400° C. and 500° C.
Furthermore, DE 100 18 371 A describes a method for fabricating a semiconductor substrate, in which a doping material is introduced into a semiconductor base material. In order to effect a spatially delimited change in the distribution of the doping material, locally delimited introduction of a quantity of heat in well-defined heating regions increases the temperature and consequently the rate of diffusion of the doping material from heating regions. The locally delimited introduction of a quantity of heat is preferably effected with the aid of a pulsed laser beam. This method is relatively complicated in terms of its practical implementation.
Maskings are necessary both for a direct implantation of, for example, high-energy boron for producing p-conducting regions and for producing an n-type doping by means of high-energy proton irradiation with a subsequent thermal step. So-called silicon stencil masks are appropriate as masks in this case since a conventional resist technique cannot be employed on account of the large thickness of the resist layer with 50 to 100 μm and the required accuracy. For a doping with high-energy protons, the application of stencil masks is problematic, however, since the high-energy implantation process for the proton doping can only be performed at the end of a complete wafer fabrication process, so that the stencil mask has to be aligned with the preceding photo-lithography planes. This alignment can only be realized with a high outlay on apparatus especially when the stencil mask has to be bonded to the wafer by means of a bonding technique.
When applying a proton irradiation to the fabrication of a compensation component, it would be conceivable to deposit p-doped epitaxial layers on an n-conducting wafer substrate and to produce the n-conducting regions—in the case of an n-channel transistor—in the drift path by a proton irradiation—masked by means of stencil masks—in the p-conducting epitaxial layers by counterdoping. The disadvantages associated with stencil masks cannot, therefore, be avoided here.
Therefore, it is an object of the present invention to specify a method for doping a semiconductor body which permits p- and n-conducting regions to be produced by means of proton irradiation without complicated masking in a semiconductor body.